With the rapid increase in population coupled with the seemingly irreversible flow of people from rural to urban areas, cities in the developing world are acquiring unplanned and uncontrolled squatter settlements at their peripheries. The provision of urban services and infrastructure in these cities is hampered by the failure of formal bureaucratic government institutions to collect appropriate information for planning, especially in areas that fall outside the remit of the formal networks. A growing number of grassroots non-government organizations (NGOs) have sought to rectify the situation by acting as intermediaries between urban slum dwellers and the government. In this paper, we review the literature on forms of intermediation by NGOs and other organizations working for citizen groups. We then present a case study of Jana Sahayog, a NGO operating in the slums of Bangalore, which employs an information-based model of NGO-mediated intervention. The paper describes the various information-based initiatives that Jana Sahayog has undertaken to open up channels of communication between citizens and the government. Jana Sahayog's experience offers valuable lessons for NGOs operating in other parts of the world.